Implement "wait for connection" feature

src/debug.h

Index: src/debug.h
diff --git a/src/debug.h b/src/debug.h
index 24f0db4133d26986c0823d0f624c63fdf82ece5b..096916ed995f4ddca99f47b491aad3a78abe7294 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -636,7 +636,7 @@ class Debugger {
                              bool* pending_exception);
 
   // Start the debugger agent listening on the provided port.
-  static bool StartAgent(const char* name, int port);
+  static bool StartAgent(const char* name, int port, bool wait_for_connection);
 
   // Stop the debugger agent.
   static void StopAgent();